Question

A circular platform is mounted on a frictionless vertical axle. Its radius R = 2 m and its moment of inertia about the axle is 200 kg m². It is initially at rest. A 50 kg man stands on the edge of the platform and begins to walk along the edge at the speed of 1 ms⁻¹ relative to the ground. Find the angular velocity of the platform and time taken by man relative to platform.

Assertion (A): Angular momentum of a system is conserved in the absence of external torque. Reason (R): Torque is the time derivative of angular momentum.

(i) What are the factors on which the M.I of a body depends? (ii) When a cat can land on its feet after a fall, which property of Physics is being used by her?

A circular ring having a diameter of 40cm and mass of 1 kg is rotating about an axis normal to its plane and passing through the center with a frequency of 10 rotations per second. Now, calculate the angular momentum about the axis of rotation.